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By Pat Rizzuto
March 11 — The Environmental Protection Agency and states are developing an ad hoc group to jointly address the safety, risk assessment and other concerns arising from cannabis growers' use of pesticides to serve the growing market for legal marijuana and marijuana products.
“The EPA has not authorized the use of any pesticide specifically on marijuana,” said Richard Keigwin, deputy director for EPA's Office of Pesticide Programs. He spoke March 9 during an Association of American Pesticide Control Officials meeting.
“EPA's position is `the label is the law,' ” Keigwin said. “If you use a pesticide, you must follow the label.”
That said, the EPA knows that the use of pesticides on marijuana crops is an issue with which a growing number of states and tribes are wrestling, he said. Twenty-three states and the District of Columbia have legalized marijuana for some purposes (see map).
The Cannabis Safety Institute, which says it is run by an advisory board of scientists, doctors, and regulatory experts to provide scientific data and expertise necessary to ensure the safety of the legal cannabis industry, issued a white paper called Pesticide Use on Cannabis.
“Pesticide use on cannabis is an emerging public health threat,” said the institute's paper published in June 2015.
“Cannabis is a high-value crop that is frequently damaged by molds and insects,” it said. Plant diseases have recently spread widely across several states, causing pesticide use to rapidly increase in response, it said.
Pesticide tolerances—that is, legal residue levels—generally range from 10 to 10,000 parts per billion (ppb), the paper said. Nearly 5 percent of cannabis concentrates, such as extracts that may be smoked directly or used to make edible products, have pesticide residues at levels that exceed 50,000 ppb.
Some concentrates contain compounds such as carbaryl, myclobutanil and chlorfenapyr at levels greater than 100,000 ppb, the paper said.
“These levels grossly exceed tolerances for pesticides on any commodity, and it is important to note that chlorfenapyr is not registered for use on any food commodities,” the white paper said.
Marley Bordovsky, assistant director in the prosecution and code enforcement section of the Denver City Attorney's Office, said concerns about pesticides for marijuana crops came to light after firefighters responded to incidents where sulfur had been used to kill mold.
The sulfur was burned and became sulfur dioxide, creating health risks for the firefighters, Bordovsky said. Sulfur dioxide can trigger asthma attacks, according to the EPA. Sulfur dioxide also can aggravate existing heart disease, EPA says.
Keigwin said the EPA understands “there are pesticide management needs we have to be mindful of.”
“It's not a local issue; it's very much a national issue,” he said.
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A legal avenue the agency has identified to aid states is Section 24(c) of the Federal Insecticide Fungicide and Rodenticide Act, Keigwin said.
That section of FIFRA permits individual states with unique or unusual pest management challenges to seek a Special Local Need (SLN) registration of a pesticide in their state when a national registration may not be necessary or appropriate, according to information the EPA posted in February.
The EPA mentioned that option in a May 19, 2015, letter to the Colorado Department of Agriculture.
EPA has not received any SLN registration requests, Keigwin said.
The pesticide office is, however, preparing to receive them, he said. For example, OPP has formed a team that would work with the state making the request, he said.
The EPA, working with states and tribes, also is developing a national working group, Keigwin said.
How states would join the group is among the procedural issues yet to be worked out, he told Bloomberg BNA.
A key issue that must be addressed is how to assess the risks of a pesticide that could be used on cannabis, which in turn may be turned into a wide variety of products, Keigwin said.
Cannabinoid-infused chocolates, gummies, lotions, toothpaste, bath salts, coffee pods, dermal patches and suppositories are just some of the types of products discussed at the meeting or identified by Bloomberg BNA afterwards.
Keigwin, who said he had not heard of cannabinoid-infused suppositories until the AAPCO meeting, said he learns of new types of merchandise being made with cannabis at every meeting he attends discussing pesticides and marijuana.
The Food and Drug Administration, which assesses the risks of pharmaceuticals delivered through suppositories, might have some risk assessment models the EPA could use, but determining whether such models were appropriate would take more work than “a simple telephone call,” he said.
Similarly, while OPP considers dermal risks as it assesses pesticides, it typically does not project exposures would occur for prolonged periods of time such as would occur from pesticide residues on a dermal patch of medical marijuana, Keigwin said.
Ashlea Frank, a consultant with Compliance Services International, said pesticide registrants may be reluctant to have their products registered for use on marijuana.
“Risk assessment methodologies have not been developed,” she said.
Assessing the risks of pesticides on marijuana will be complicated, Frank said.
Registrants likely will not want to help develop methodologies, because the product on which their pesticide would be used violates federal law, Frank said.
A registrant also would not want already-approved uses of its product threatened by a new application that would reduce space in the “risk cup,” she said.
By “risk cup,” Frank referred to an analogy the EPA commonly uses.
For each pesticide active ingredient, EPA determines a total level of acceptable risk, that is the total exposure that a person could receive every day over a 70-year lifetime without significant risk of a long-term or chronic non-cancer health effect.
The total exposure includes residues that could occur from dietary or non-dietary exposures.
The total, or maximum, level of acceptable risk represents a full risk cup.
If the risk cup “overflows,” a registrant may have to cancel some uses of its pesticide, change the product label to reduce the amount of pesticide used or take other actions to reduce the use of its product.
Ultimately, Frank said, pesticide registrants like other companies are concerned about how the general public views them.
Many people don't like marijuana and that perception makes companies leery to enter this market, she said.
To contact the reporter on this story: Pat Rizzuto in Washington at firstname.lastname@example.org
To contact the editor responsible for this story: Larry Pearl at email@example.com
The EPA's website on pesticide use on marijuana is available at http://www.epa.gov/pesticide-registration/pesticide-use-marijuana.
Pesticide Use on Cannabis is available from the Cannabis Safety Institute at http://cannabissafetyinstitute.org/white-papers/.
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